Safety, Stability and Immunogenicity of an Oral DNA Vaccine Against Newcastle Disease
鸡新城疫口服DNA疫苗的安全性、稳定性与免疫效力

Mice and 3 day old chickens were orally inoculated with the recombinant attenuated Salmonella typhimurium strain ZJ111 carrying pcDNA3 F expression plasmid encoding the fusion protein of Newcastle disease virus (NDV). The results showed that ZJ111/pcDNA3 F was relatively safe. The recombinant plasmid pcDNA3 F was stable within the host stain ZJ111 in vitro and in vivo as shown by restriction enzyme analysis and PCR identification of the F gene. In an experimental vaccination study, 3 day old chickens were orally immunized with ZJ111/pcDNA3 F with a dose of 10 8cfu per chicken and boosted two weeks later. At week 4 post boosting, all chickens were challenged with a lethal dose of a virulent NDV strain F 48 E 9 The results showed that oral vaccination with ZJ111/pcDNA3 F induced stronger humoral and cellular immune responses than intramuscular immunization with naked pcDNA3 F plasmid. It also exhibited higher protection rate than the latter (66 7% vs 50%). This study indicates that the DNA vaccine using attenuated Salmonella typhimurium as delivery carrier had good safety, stability and immunogenicity and exhibited good potential of low cost and convenience for poultry disease control.